This invention relates to the liquid level control art, and more particularly, to apparatus for maintaining the water level in a swimming pool, spa or the like within predetermined maximum and minimum levels.
The water level within a swimming pool, spa or the like should be kept within a rather narrow range of elevation level change in order that the skimming portion of the recirculating and filter apparatus will function properly. This level is usually maintained by simply observing the water level and supplying makeup water from a line source with a manually operated valve. However, because the volume of water necessary to make up even a slightly lower level is considerable, the time necessary to bring the water to the desired level may be several hours, a circumstance which renders the task unpleasant and additionally, brings about the possibility of over filling due to failure to monitor the progress of the operation carefully enough. Thus, it will be apparent that it would be highly advantageous to provide automatic means for maintaining the water level of swimming pools or like liquid reservoirs within predetermined maximum and minimum levels without the need for manual supervision or intervention which includes a fail safe back up system incorporated therein to prevent overfill if the automatic system fails while in the fill mode.
There are numerous automatic fill systems in the art directed to fill control of swimming pools and the like. These systems generally utilize float valve means to control the flow of new or additional water into the reservoir. These systems employ either mechanical or electrical valve control means responsive to float vertical position. Although most of the prior art devices use a single liquid input control valve associated with a float, some prior art devices include a reservoir within the valve means separating input and output conduits and includes a float actuated valve in both the input and output conduits whereby a single leaking valve will not cause over filling of the swimming pool or reservoir.
U.S. Pat. No. 2,068,138 teaches a two stage float actuated valve system utilizing a pair of internal reservoirs each with a float and valve for controlling the flow of liquid into the reservoirs. One float and valve combination is the primary liquid flow control valve and the second acts as a backup in the event the primary valve fails to close off liquid flow into the reservoirs. Both valves are actuated between open and closed states.
In my U.S. Pat. No. 4,592,098 issued on 06/03/86, I have advanced the pool reservoir fill control art by providing a level control device that is satisfactory for the purpose intended; However, in my prior art device resetting of the secondary or safety over fill valve required shutting off the liquid supply line and then bleeding the liquid under pressure from the line causing inconvience if an overfill of the pool reservoir should occur preventing practical use of the device when installed in pool reservoir cleaners known in the industry as surface skimmers. Further, it was found on occasion that the primary float which operates the normal fill and level maintenance of the pool reservoir has a tendency to occasionally bind on the housing adjacent thereto preventing the desired pool reservoir level maintenance.